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ADM4851 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADM4851
Beschreibung Half-Duplex and Full-Duplex RS-485/RS-422 Transceivers
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 16 Seiten
ADM4851 Datasheet, Funktion
5 V, Slew-Rate Limited, Half-Duplex and
Full-Duplex RS-485/RS-422 Transceivers
ADM4850/ADM4851/ADM4852/ADM4853/ADM4854/ADM4855/ADM4856/ADM4857
FEATURES
EIA RS-485-/RS-422-compliant
Data rate options
ADM4850/ADM4854: 115 kbps
ADM4851/ADM4855: 500 kbps
ADM4852/ADM4856: 2.5 Mbps
ADM4853/ADM4857: 10 Mbps
Half- and full-duplex options
Reduced slew rates for low EMI
True fail-safe receiver inputs
5 μA (maximum) supply current in shutdown mode
Up to 256 transceivers on one bus
Outputs high-Z when disabled or powered off
−7 V to +12 V bus common-mode range
Thermal shutdown and short-circuit protection
Pin-compatible with the MAX308x
Specified over the −40°C to +85°C temperature range
Available in 8-lead SOIC, LFCSP, and MSOP packages
Qualified for automotive applications
APPLICATIONS
Low power RS-485 applications
EMI-sensitive systems
DTE-DCE interfaces
Industrial control
Packet switching
Local area networks
Level translators
GENERAL DESCRIPTION
The ADM4850/ADM4851/ADM4852/ADM4853/ADM4854/
ADM4855/ADM4856/ADM4857 are differential line transceivers
suitable for high speed half- and full-duplex data communication on
multipoint bus transmission lines. They are designed for balanced
data transmission and comply with EIA Standards RS-485 and
RS-422. The ADM4850/ADM4851/ADM4852/ADM4853 are half-
duplex transceivers that share differential lines and have separate
enable inputs for the driver and receiver. The full-duplex
ADM4854/ADM4855/ADM4856/ADM4857 transceivers have
dedicated differential line driver outputs and receiver inputs.
The parts have a 1/8-unit-load receiver input impedance, which
allows up to 256 transceivers on one bus. Because only one driver
should be enabled at any time, the output of a disabled or pow-
ered-down driver is three-stated to avoid overloading the bus.
The receiver inputs have a true fail-safe feature, which ensures
a logic high output level when the inputs are open or shorted.
This guarantees that the receiver outputs are in a known state
Rev. D
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
FUNCTIONAL BLOCK DIAGRAMS
VCC
ADM4850/ADM4851/
ADM4852/ADM4853
RO R
RE A
DE B
DI D
GND
Figure 1.
VCC
ADM4854/ADM4855/
ADM4856/ADM4857
RO R
A
B
DI D
Z
Y
GND
Figure 2.
before communication begins and when communication ends.
The driver outputs are slew-rate limited to reduce EMI and data
errors caused by reflections from improperly terminated buses.
Excessive power dissipation caused by bus contention or by output
shorting is prevented with a thermal shutdown circuit.
The parts are fully specified over the commercial and industrial
temperature ranges and are available in 8-lead SOIC, LFCSP
(ADM4850/ADM4851/ADM4852/ADM4853), and MSOP
(ADM4850 only) packages.
Table 1. Selection Table
Part No.
Half-/Full-Duplex
ADM4850
Half
ADM4851
Half
ADM4852
Half
ADM4853
Half
ADM4854
Full
ADM4855
Full
ADM4856
Full
ADM4857
Full
Data Rate
115 kbps
500 kbps
2.5 Mbps
10 Mbps
115 kbps
500 kbps
2.5 Mbps
10 Mbps
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2004–2012 Analog Devices, Inc. All rights reserved.






ADM4851 Datasheet, Funktion
ADM4850/ADM4851/ADM4852/ADM4853/ADM4854/ADM4855/ADM4856/ADM4857
ABSOLUTE MAXIMUM RATINGS
Table 7.
Parameter
VCC to GND
Digital I/O Voltage (DE, RE, DI, RO)
Driver Output/Receiver Input Voltage
Operating Temperature Range
Storage Temperature Range
θJA Thermal Impedance
SOIC
LFCSP
MSOP
Lead Temperature
Soldering (10 sec)
Vapor Phase (60 sec)
Infrared (15 sec)
Rating
6V
−0.3 V to VCC + 0.3 V
−9 V to +14 V
−40°C to +85°C
−65°C to +125°C
110°C/W
62°C/W
133.1°C/W
300°C
215°C
220°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
Rev. D | Page 6 of 16

6 Page









ADM4851 pdf, datenblatt
ADM4850/ADM4851/ADM4852/ADM4853/ADM4854/ADM4855/ADM4856/ADM4857
SWITCHING CHARACTERISTICS
3V
0V
B
VOD
A
5V
1.5V
1/2VOD
90% POINT
tPLH
1.5V
tSKEW = |tPLH – tPHL|
tPHL
90% POINT
10% POINT
0V
tR
10% POINT
tF
Figure 24. Driver Propagation Delay, Rise/Fall Timing
DE
A, B
A, B
1.5V
tZL
2.3V
tZH
2.3V
1.5V
tLZ
3V
0V
VOL + 0.5V
VOL
tHZ
VOH
VOH – 0.5V
0V
Figure 26. Driver Enable/Disable Timing
A, B
0V
0V
tPLH
tPHL
VOH
RO
1.5V
tSKEW = |tPLH – tPHL|
1.5V
VOL
Figure 25. Receiver Propagation Delay
RE 1.5V
tZL
1.5V
tLZ
3V
0V
RO
1.5V
OUTPUT LOW
VOL + 0.5V
tZH
OUTPUT HIGH
tHZ
VOL
VOH
RO
1.5V
VOH – 0.5V
0V
Figure 27. Receiver Enable/Disable Timing
Rev. D | Page 12 of 16

12 Page





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